Nozzle flexibility

Dear Richard/Dave,

In Nozzle flexibility by WRC 297/ API 650/PD 5500 Methods, I observed that for Vessel node number entry in brackets (optional) is there.

I checked the help file but I didn’t understand this statement- “if not given the Nozzle node is connected via the stiffnesses to a point fixed rigidly in space”

Can you please clarify?

You would specify that "optional" node number if (and only if) that "optional" node number is also modeled in your system. Take a look at the nozzle/vessel modeling in the Applications Guide for details.

My question is to Dave is that in ASME B 31.3 2006 ,SL is compared to Sh x W where W is weld joint strength reduction factor.
In ASME B 31.3 2008 ,SL is compared to Sh.
Then how about the effect of weld joint strength reduction factor in sustained allowable.

Thanks

I think it is Considering from 2004 code(CAESAR II VERSION 5.0) to till date .

A Code change for circumferential welds turned the mandatory use of W (Wc in C2) in sustained allowable stress to optional.

The Edition of the Piping Codes addressed by c2 can be found:

a) In the Quick Reference Guide, and
b) In the header of the Stress Reports.

Dear Dave

Earlier in B 31.3 2006 code the effect of Weld joint strength factor was very clear , as i understood-
1.To calculate wall thickness
2.To reduce sustain allowable(Code used Sh x W to take the effect)
and
Caesar 5.2(This has used ASME B 31.3 2006 edition and it is taking the effect of this facor by reducing Sustained allowable)


Now in B 31.3 2010 code the effect of Weld joint strength factor is not very clear, as i understood-
1.To calculate wall thickness (Same as earlier in B 31.3 2006)
2.Code said''THE DESIGNER IS RESPONSIBLE FOR THE APPLICATION OF WELD JOINT STRENGTH REDUCTION FACTOR''

Now Caesar 6.1-This provides just an ON/OFF option in configuration file but how it is taking the effect of this factor into calculations?
Will the allowables be reduced?
or something else.

So My question is how weld joint strength factor is taking part in stress calculation as per ASME B 31.3 2010 and CAesar 6.1 ?

Thanks

In C2 you have two terms - Wl and Wc - to define this weld joint strength reduction factor. If you specify Wl,it will be used in the wall thickness calculation. If you specify Wc AND if the switch is set in Config, then C2 will reduce the sustained allowable stress by this multiplier.

Dear Dave,

Can you please clarify these doubts regarding “W”?

1. If I am not clicking (NO TICK) the option SEAM WELDED then what value of WL CAESAR-II is using for calculating thickness of the pipe.
Where this thickness t= PD/2(SEW+PY) is used. For hoop stress cal.
I made calculations of HOOP stress BY LAMES EQUATION the results are matching, BUT I used the inputted thk (ex: STD)

2. If I am using the option by clicking (TICK) the option SEAM WELDED then from where the value of WL should be taken by the user? It is taking a value of 1 only.

3. “Table 302.3.5 WELD JOINT STRENGTH REDUCTION FACTOR, W” table values are only WC values or only WL values or BOTH.

4. Is this statements are correct.
WL= longitudinal weld reduction factor (for longitudinal weld joints)
WC= circumferential weld reduction factor (for circumferential weld joints)

Please correct me if I am wrong.

1. If seam-welded is not selected, Wl=1
2. If seam-welded is selected and Wl is null, Wl=1
3. The Code's single W is segregated into two CAESR II values: Wl & Wc - the former for wall thickness and the latter for the (optional) adjustment for the allowed limit for sustained stress.
4. Yes

Sir Dave,

Thanks for your reply,

1. Is my understanding is correct.

If selected then WL varies from (null) i.e., 0 to 1.

If not selected WL=1 ALWAYS.

2. If selected (seam welded) then WL value from where it is taken?

3. Where this WL is used in CAESAR-II calculations. (From last post you said thickness. But where that thickness is used, because user already entering the thickness value.)

4. CAESAR-II is taking the value of WC automatically from the Table 302.3.5 WELD JOINT STRENGTH REDUCTION FACTOR, then why not WL.

Please correct me if I am wrong.

CAESAR II will generate a warning (not error) if the user-entered pipe thickness is less than the required purchase thickness for the temperature-pressure service required. CAESAR II uses this WL in the required pressure thickness calculation. If it is not specified WL=1.
The use of W (our WC) is optional for circumferential welds - the Code says "The designer is responsible for the application of weld joint strength reduction factors to welds other than longitudinal and spiral". Understanding that an earlier edition of B31.3 explicitly included this WC in setting the allowable sustained stress, current reading has this as an option to be considered by the designer.
Read 302.3.5(e)

Sir Dave,

Thank you for your reply,

About WC concept is clear. My Doubt is only on WL.

1. As you said ”CAESAR II uses this WL in the required pressure thickness calculation”. Where this thickness is used in CAESAR-II calculations, in hoop stress?

2. If selected the option SEAM WELDED then from where the value of WL (in between zero to one) should be taken by the user?

3. Why for WL user has to enter, I mean CAESAR-II is taking the value of WC automatically from the Table 302.3.5, then why not WL.

please correct me, if I am wrong.

Any comments?

1) it's not. This value is used for the minimum wall thickness calculation. This minimum thickness valur is " information only", it affects nothing in c2.

2) interpolate for your temperature in the appropriate material category.

3). This is an element property and will be duplicated forward by the software.

Sir Richard,

Thanks a lot for your reply,

Please check my statements, whether my understanding is correct or not from your reply.

1. So for Hoop stress calculations CAESAR-II used- “only user entered thickness ” not with the minimum wall thickness(t=PD/2(SEW+PY)

2. Where I have to interpolate this temperature & material- you mean from “from the Table 302.3.5 WELD JOINT STRENGTH REDUCTION FACTOR”?

3. CAESAR-II is taking the value of WC automatically from the Table 302.3.5. Then why not WL. What is the problem for taking WL also automatically?

Sorry Richard, I am unable to understand the answer for my 3rd question. “This is an element property and will be duplicated forward by the software”. Can you please elaborate shortly.

Please correct me if I am wrong.

1). Yes

2). Yes

3). I can't answer right now, I'm out of the country, away from my office.

I will wait sir for your reply.

any comments on 3rd question?

CAESAR-II is taking the value of WC automatically from the Table 302.3.5. Then why not WL. What is the problem for taking WL also automatically?

Sorry Richard, I am unable to understand the answer for my 3rd question. “This is an element property and will be duplicated forward by the software”. Can you please elaborate shortly.

We are looking at it now.

Wl / Wc operations just reverified. Assuming your termperature is in the creep range for the material class, the values specified (or acquired from the material database) will be used.

Sir Richard,

Thanks for your reply,

1. For example: User entered WC value 0.5 (BY MISTAKE) & from the table CAESAR-II interpolated value is 0.95 (CORRECT VALUE) then for calculation of minimum thickness value which WC value is used by CAESAR-II?

2. Code given a DEFINED VALUES to WL based on temperature and material then again why CAESAR-II given this option to user to enter WL. Is there any reason behind that? CAESAR-II can automatically do this interpolation and take that WL value.

3. I think “The value of WC should be equal to WL”, whether these values are varies to each other in any case? Because both values are taken from the table 302.3.5 by interpolation based on material and temperature.

Any comments

Any comments..

1) c2 will use the input value (0.5). If the user changes the value we will assume the user knows what he is doing and use his data.

2) Yes c2 can interpolate this value. However, users do need the ability to specify this also - suppose you want to use a material not in the material database, or suppose you qualify the weld and want to use 1.0?

3) Yes this is correct. One is for the longitudinal direction and one is for circumferential.

Thanks Richard
Now its clear.